Artificially reconstituted freestanding planar lipid bilayers play an important role in ion channel electrophysiological studies and are used in pharmaceutical and sensor applications. The technological utility of lipid membranes can be limited, however, by their characteristic short lifetime and fragility. These shortcomings have necessitated membrane formation be at the time and point of use.
Recently, research has focused on the creation of lipid bilayer membranes of two primary varieties: freestanding (communicating with fluid on each side) and solid-supported (communicating with a fluid one side and a surface on the other). Freestanding membranes can be made using traditional “painting” methods, in which the membrane precursor is dissolved in an organic solution and spread over an orifice. These membranes are difficult to form, have short lifetimes, and are fragile. In solid supported membranes it can be problematic to measure trans-membrane ionic transport electrically because of the inaccessibility of one side of the membrane. Furthermore, since the solid support stabilizes the membrane extremely well, defects in the membrane can occur without any effect on the rest of the membrane, which can severely complicate transport measurements.
Although recent work with gel encapsulation has improved membrane robustness and lifetime significantly (Jeon et al., J. Am. Chem. Soc. 128:42-43, 2006; Kang et al., J. Am. Chem. Soc. 129:4701-4705, 2007; Shim and Gu, Anal. Chem. 79:2207-2213, 2007; Malmstadt et al., Adv. Mat. 20:84-89, 2008) a degree of membrane longevity, robustness, and portability compatible with commercial shipping has not yet been demonstrated. Furthermore, the process of membrane formation (Mueller et al., Nature, 194:979-980, 1962; Montal and Mueller, Proc. Nat. Acad. Sci. U.S.A. 69:3561-3566, 1972) still requires significant operator involvement for chamber assembly and the membrane formation process, limiting manufacturability. Microfluidic devices capable of creating and measuring lipid bilayers require manipulation of multiple aqueous/air/organic fluidic phases or their manual deposition to facilitate lipid bilayer membrane formation.
Therefore, there remains a need for methods, compositions, and devices that overcome these deficiencies and that effectively provide for membranes and/or membrane precursors with improved robustness, stability, and longevity. The methods, compositions, and devices disclosed herein address these and other needs.